Monitoring device

ABSTRACT

A monitoring apparatus is provided which can ensure the prevention of a paper break even in a poor installation environment. A light source ( 9 ) illuminates light ( 9   a ) on a lateral edge ( 1   a ) of wet paper ( 1 ) and a camera ( 5 ) captures light ( 9   b ) reflected therefrom. The camera ( 5 ) is a micro camera and completely covered by a camera box ( 10 ). The camera box ( 10 ) has an observation window ( 10   a ) which is made of a transparent member, at the lens side ( 5   a ) of the camera ( 5 ). The outer surface of the observation window ( 10   a ) is coated and an air curtain ( 12   a ) that flows from above to below prevents staining caused by mist. The air curtain ( 12   a ) is formed in such a manner that air that is continuously supplied inside a cover ( 11 ) flows along the outer surface of the observation window ( 10   a ) from an opening portion ( 11   a ). A color image obtained by the camera ( 5 ) is subjected to image processing in an image processing device ( 6 ) and the resulting image is projected on a monitor TV ( 7 ), so that variations of the release point ( 3 ) can be monitored. This allows for forecasting of a machine abnormality leading to a paper break.

This application is a 371 of PCT/JP02/05207 filed 29 May 2002.

TECHNICAL FIELD

The present invention relates to monitoring apparatuses for a monitoringstrip-shaped object running continuously, and relates to a monitoringapparatus for monitoring, for example, the flow of paper in a papermachine.

BACKGROUND ART

For a conventional paper making machine, during operation, an operatorperiodically patrols and monitors it to check the operational state, soas to ensure stable operation of the machine. In order to detect theoccurrence of a paper tear, for example, a paper-tear detecting sensorwhich is constituted by an infrared emitter arranged at the obverse sideof running paper and a detector arranged at the reverse side of therunning paper is installed in the machine. When the paper tears, thedetector detects infrared light, so that the paper tear can berecognized.

With such a paper-tear detecting sensor, while a paper tear can bedetected, its cause cannot be determined. For this reason, in recentyears, a camera and a light source have been installed around themachine to monitor its state, and also, the monitored state is recordedin a video recorder or a digital memory, so that how the paper breakscan be replayed. In this manner, the operator can determine the cause.This approach, however, merely replays a recorded scene of the situationin which the paper tore, and thus cannot prevent a paper break or tearfrom occurring. Recently, paper machines have become increasinglyfaster, and thus it is important to minimize the occurrence of problems,such as paper breaks, in order to improve the production efficiency.

An approach for overcoming the above-described problems is disclosed in,for example, Japanese Unexamined Patent Application Publication No.2000-154489. In this approach, a light source is arranged at one side ofthe paper surface of paper running on rolls in a paper machine and aplurality of cameras are arranged at the other side, and images of thelight transmitted through the running paper from the light source arecaptured by the plurality of cameras. The amount of variation in releasepoints of the running paper from a roll is quantitatively determined sothat the paper machine is monitored for an abnormality.

With the above-described approach, however, release points across theentire width of the running paper are monitored by a plurality ofcameras, and thus, when the image-capturing environment is poor due to,for example, the generation of a large amount of mist in the vicinity ofa monitoring portion, it is difficult to determine the amount ofvariations in the positions of release points across the entire width.Further, since the monitoring equipment is installed at both papersurfaces of the running paper, when space for the monitoring portion islimited, it is difficult to install the monitoring equipment inpractice. Although this approach is superior in that monitoring isperformed using transmitted light that can provide a clearer image, itis inconvenient in practice.

DISCLOSURE OF THE INVENTION

The present invention has been made in view of the above, and an objectof the present invention is to provide a monitoring apparatus thatdetects a running paper abnormality more reliably even in a poorinstallation environment, that can prevent a running paper abnormalityand paper breaking from occurring. Another object of the presentinvention is to prevent abnormal running of a strip-shaped objectflowing continuously.

The present invention has been made to overcome the above-describedproblems, and is characterized in that light from a light source isdirected to a lateral edge of a strip-shaped object flowing continuouslyand is reflected, an image of the object is captured with the reflectedlight, and the image is subjected to image processing, therebyquantitatively monitoring the amount of variations in the running pathof the object.

The present invention is applicable, for example, for monitoring a spotwhere paper tends to be broken in a paper machine. That is, light fromthe light source is illuminated on running paper in the paper machine,an image of the running paper is captured with light reflectedtherefrom, and the captured image is subjected to image processing, sothat the amount of variations at the release point of the running paperfrom a roll is quantitatively monitored to diagnose abnormalities in thepaper machine.

A specific configuration of the present invention includeslight-emitting means for illuminating light on a lateral edge of paperrunning on a roll in a paper machine, image-capturing means forcapturing an image of light that comes from the light-emitting means andthat reflects from the lateral edge of the paper, image-processing meansfor processing the image captured by the image-capturing means, anddiagnosing means for diagnosing an abnormality in the paper machine byquantitatively monitoring the release point of the paper from the rollfor its varying positions in accordance with the result of processing bythe image processing means.

The light-emitting means and the image-capturing means can be installedat only the machine side.

The present invention is particularly applicable to a case in which theimage-capturing environment at the monitoring portion is poor due, forexample, to the generation of mist. In this case, it is preferable toprovide means for preventing staining of the light-receiving window ofthe image-capturing means. Further, for the light source of thelight-emitting means in this case, it is preferable to use ametal-halide light source.

It is desirable to pre-set abnormality diagnosis conditions based on theamount of variations associated with an object in the normal state. Whenthe abnormality diagnosis conditions are affected by variousenvironmental conditions, it is preferable to change the abnormalitydiagnosis conditions as the environmental conditions change. Forexample, in the diagnosing means, the conditions for diagnosing theabnormality are adapted so as to be changeable in accordance with thebasis weight and the draw amount of the paper.

It is further preferable to have a mechanism that performs automaticcontrol for maintaining normal operation when an abnormality isdiagnosed and determined. That is, adjusting means is further providedso that, when the abnormality is found, the adjusting means adjusts thedraw amount in accordance with a result of the diagnosis to therebyprevent paper tear.

It is to be noted that the “basis amount” herein refers to the weightper 1 m² sheet of paper and the “draw amount” refers to the degree oftension of the paper web between individual sections in a paper machineand is determined by speed differences among driving rolls of theindividual sections in the paper machine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view schematically illustrating a press part of a papermachine to which a monitoring apparatus according to one embodiment ofthe present invention is applied.

FIG. 2 is an enlarged view of the exit of a center roll in the presssection shown in FIG. 1.

FIG. 3 is a system block diagram of the monitoring apparatus of theembodiment of the present invention.

FIG. 4( a) is a plan view showing a state in which the monitoringapparatus is installed in the vicinity of the exit of the center rollshown in FIG. 2 and FIG. 4( b) is a front view of the same state.

FIG. 5( a) is a longitudinal sectional view of a camera box, and FIG. 5(b) is a front view of the camera box, as viewed from an observationwindow side.

FIG. 6 is a graph showing a release-point variation obtained from animage processing device, the vertical axis indicating the amount ofvariation from a reference and the horizontal axis indicating time (s).

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of a monitoring apparatus according to the presentinvention will now be described with reference to drawings.

A description is given of a case in which a monitoring apparatusaccording to one embodiment of the present invention is applied to apaper machine. In this case, the monitoring apparatus monitors theoperational state of the paper machine.

The paper machine generally includes a stock inlet, a wire section (wirepart), a press section (press part), and a dryer section (dryer part).In addition, the paper machine typically has a calender section(calender part) and a reel section (reel part). As one example, a papermaking process in the case of a Fourdrinier paper machine will bebriefly described. A carefully selected pulp liquid is sprayed over anendless wire from the stock inlet. The resulting pulp is dehydrated in asuction box and is passed through a slice to have a uniform thickness.In the press section, felts are rotated in conjunction with press rolls,and, at the same time when water is squeezed, the surface of the paperis smoothed (paper web formation). Subsequently, the paper is heated anddried in the dryer section. In the calender section, the paper surfaceis smoothed and calendered. Lastly, the web is wound by the reelsection.

The press section at which the monitoring apparatus is provided will nowbe described. The press section in this embodiment shown in FIG. 1 hasfour stages of presses, i.e., a first press (1P) to a fourth press (4P),and is provided with a center roll 2, a press top roll 14, a pressbottom roll 15, a suction roll 16, and a paper roll 4. These rolls 2, 14to 16, and 4 together with felts 17 convey wet paper 1 in the directionof arrow A. This wet paper 1 is a paper web that was formed by the wirepart and that has been transferred to the press part. The felts 17 movein the directions of arrows B. To clean the center roll 2, a shower (notshown) is provided in the vicinity thereof.

At the center roll portion of the press section, the wet paper 1 isseparated from the felt 17, further separated (released) at the releasepoint 3 from the surface of the center roll 2, as shown in FIG. 2, andconveyed to the next process via the paper roll 4. The wet paper 1 isnot supported by the felt 17 or the like (open draw) at the releasepoint 3, which is, therefore, a spot at which a paper is most likely tobreak or tear. Thus, monitoring of the release point 3 is a criticalfactor for stable operation while preventing paper from tearing. Themonitoring apparatus according to the embodiment of the presentinvention monitors variable conditions at the vicinity of the releasepoint 3. The release point 3 herein refers to a point at which an edgein the width direction of the wet paper 1 is separated from the centerroll 2.

Individual elements of the monitoring apparatus will be described withreference to FIGS. 3 to 5. As shown in FIG. 3, the monitoring apparatusincludes a camera 5, an image processing device 6, a monitor TV 7, acomputer 8, and a light source 9.

The camera 5 is connected to the image processing device 6, and theimage processing device 6 is connected to the monitor TV 7 and thecomputer 8. The light source 9 is a metal-halide light source (metalhalide lamp) in this embodiment. This metal-halide light source is ahigh-intensity discharge lamp that emits light by dischargingelectricity in a mixture of metallic vapor and halide dissociationproducts and is a powerful light source whose wavelength distribution isflat. The use of the metal-halide light source can improvedifferentiation from peripheral equipment in image processing, by makinggood use of the fact that the wet paper 1 is white.

As shown in FIGS. 4( a) and 4(b), the camera 5 is provided at the sameposition as the light source 9, and both the light-emitting surface ofthe light source 9 and the lens of the camera 5 are directed to alateral edge 1 a of the wet paper 1. Thus, the light source 9illuminates light 9 a on the lateral edge 1 a of the wet paper 1 and thecamera 5 captures light 9 b reflected therefrom. This camera 5 iscompletely covered by a camera box 10, as shown in FIGS. 5( a) and 5(b).This camera box 10 has an observation window 10 a which is made of atransparent member on the lens side 5 a of the camera 5, so that thecamera 5, even in the camera box 10, can capture external light.

The outer surface of the observation window 10 a is covered with acoating for stain prevention, and the mechanism illustrated belowfurther prevents the observation window 10 a from staining. Namely, acover 11 having an opening portion 11 a is attached to the upper side ofthe observation window 10 a of the camera box 10. Air 12 is continuouslysupplied inside the cover 11, so that an air gap, i.e., an air curtain12 a flowing from above to below, is formed at the outer surface of theobservation window 10 a. This air curtain 12 a serves to prevent mist orthe like from attaching to the outer surface of the observation window10 a, thereby making it possible to remove or reduce an obstructioncaused by mist when the camera 5 captures an image. As described above,while the coating and the air curtain 12 a are used in this embodimentto prevent mist attachment and to remove attached mist, the presentinvention is not limited thereto. For example, the arrangement may besuch that a wiper (now shown) is used to wipe off mist attached to theouter surface of the observation window 10 a. Alternatively, thearrangement may be such that the observation window 10 a is rotated togenerate a centrifugal force, thereby removing attached mist. The camera5 is a micro color-CCD camera which thus allows for a reduction in theoutside dimensions of the camera box 10. This reduces the space forinstallation, thereby allowing for installation in places where space istight. Further, the size of the observation window 10 a is reduced,thereby allowing for a reduction in the proportion of staining due tomist attachment.

It should be noted that the mist is generated by the shower (not shown)for cleaning the center roll 2, as described above, and additionally,the mist is generated by a doctor (not shown) provided at the centerroll 2. Thus, an anti-mist measure is important for release-pointmonitoring by the camera 5.

While the combination of the camera 5 and the light source 9 is arrangedat the machine side in this embodiment, the present invention is notlimited thereto. Thus, the combinations may be arranged at both themachine side and an operation side so as to monitor the edges at bothsides. When they are arranged on both machine and operation sides, thereis a concern that light from the light source at one side may enter thecamera on the other side. Even in this case, however, since the wetpaper 1 generally has a width of as much as a few meters, the camera isnot affected by light from the light source at the other side.Processing of an image obtained in this manner will now be described. Acolor image obtained by the camera 5 is analyzed by the image processingdevice 6, and unwanted lines are eliminated. That is, a monochrome imageis extracted from the color image by using a green component, and anoise component is removed from the monochrome image. Thereafter, thelateral edge of the wet paper 1 is emphasized using a spatial filter andbinarized. A roll portion in the image is registered as a mask image anda crease at the release point of the lateral edge 1 a is extracted fromthe binary image from which the mask image is removed. This imageprocessing is simple and involves an efficient algorithm; therefore, itcan be executed at a high speed and can also analyze the frequency ofvariations at the lateral edge.

After image processing, an image is output to the monitor TV 7 (see FIG.3). The image on the monitor TV 7 provides the same viewpoint as that ofan operator performing visual monitoring, and therefore the operatorfeels familiar and comfortable.

A graph obtained from the above-described processing will now bedescribed with reference to FIG. 6. In this figure, the vertical axisindicates the amount of variation from a reference and the horizontalaxis indicates time (s).

The release point 3 of the wet paper 1 varies as shown in FIG. 6, fromthe graph of which the state of variations can be determined. Thus,allowable values (abnormality diagnosis conditions) of the amount andperiod of variations at the release point 3 can be set in the computer 8(see FIG. 3). The settings of those abnormality diagnosis conditions canbe appropriately changed depending on the basis weight and the drawamount of the paper. In this embodiment, while the computer 8 has afunction (diagnosing means) for diagnosing an abnormality in the papermachine by quantitatively monitoring the amount of variation in therelease point, the diagnosing means may be provided separately from thecomputer 8. In this manner, a machine abnormality leading to a paperbreak can be forecast. When an abnormal event occurs, for example, analarm or the like can also be set off to notify the operator of theabnormal event, so that the draw amount can be changed so as to preventa paper break. That is, the press part can be controlled by adjustingthe draw amount so as to adjust the shape of the profile. The amount ofvariation in the release point is important in forecasting a paper breakand can be used to prevent a paper break. The configuration may be suchthat the adjustment of the draw amount is automatically controlled byadjusting means (not shown) connected to the computer 8.

In addition, based on the amount of variations at the release point, thereplacement time of parts, such as the felt, can be determined.Immediately after replacement of the felt, when the draw is constant,the dehydration state is poor so that the release point fluctuates. Therelease point is controlled to a constant release position by changingthe draw. The felt settles in two or three days, thus improving thedehydration state, and the release position is set in place by changingthe draw. When the paper machine is operated under these conditions, thedehydration state begins to deteriorate at a certain time to cause therelease point to fluctuate. This commonly results in earlier replacementof parts. Accordingly, staining and the surface condition of thereplaced felt are quantitatively analyzed and are compiled into adatabase together with the draw amount and the amount of variation inthe release point. This allows for determination of adequate replacementtime considering both the paper quality and economical factors such asthe cost of parts.

Thus, it is possible to support stable operation and to determine thecause of a paper break, since the position of the release point and themargin and period of the variation thereof are strongly correlated withthe draw, staining of the paper machine and parts, and a change in rawmaterial. In conjunction with the need for higher-speed paper machinesin recent years, the operation process and management for stainprevention as well as mechanical stability have become important, andthe present invention can reliably cope with the need.

INDUSTRIAL APPLICABILITY

In a monitoring apparatus according to the present invention, light froma light source is illuminated on a lateral edge of a strip-shaped objectrunning continuously and is reflected, an image of the object iscaptured with the reflected light, and the image is subjected to imageprocessing, thereby quantitatively monitoring an amount of variations inthe running path of the object. This allows for continuous recognitionof changes in the running object and allows for accurate monitoring.

A monitoring apparatus according to the present invention includeslight-emitting means for shining light on a lateral edge of paperrunning on a roll in a paper machine, image-capturing means forcapturing an image of light that is illuminated by the light-emittingmeans and that is reflected by the lateral edge of the paper,image-processing means for processing the image captured by theimage-capturing means, and diagnosing means for diagnosing anabnormality in the paper machine by quantitatively monitoring the amountof variations at the release point of the paper from the roll inaccordance with the result of processing by the image processing means.This allows for continuous recognition of changes in the path of therunning paper and allows for accurate monitoring.

Installation of the light-emitting means and the image-capturing meansat only the machine side does not provide an obstacle to visualobservation and operation by the operator since there is no need toinstall those means at the operation side, which can improve theusability and operability.

Further providing means for preventing staining of the light-receivingwindow of the image-capturing means can remove or reduce an obstacle incapturing an image to thereby provide a satisfactory image.

The use of a metal-halide light source as the light source for thelight-emitting means can improve differentiation from peripheralequipment at the time of image processing, thereby allowing for accuratemonitoring even in a poor image-capturing environment.

In the diagnosing means, setting the conditions for diagnosing anabnormality so as to be changeable in accordance with the basis weightand the draw amount of the paper can improve the diagnostic accuracy,thereby allowing for optimal monitoring.

Further providing an adjusting means which adjusts the draw amount inaccordance with the result of the diagnosis of the abnormality canadjust the shape of the profile so as to prevent paper tear and controlthe press part and the like.

1. A monitoring apparatus characterized by comprising light-emittingmeans for shining light on a lateral edge of paper running on a roll ina paper machine; image-capturing means, completely covered by the box,having a light receiving window, for capturing an image of light that isshined by the light-emitting means and that is reflected by the lateraledge of the paper; means for preventing staining of the light receivingwindow of the box; image-processing means for processing the imagecaptured by the image-capturing means; and diagnosing means fordiagnosing an abnormality in the paper machine by quantitativelymonitoring an amount of variation in a release point of the paper fromthe roll in accordance with a result of processing by the imageprocessing means.
 2. The monitoring apparatus according to claim 1,characterized in that the light-emitting means and the image-capturingmeans are provided only at a machine side.
 3. The monitoring apparatusaccording to claim 1, characterized in that a metal-halide light sourceis used as a light source for the light-emitting means.
 4. Themonitoring apparatus according to any one of claims 1, 2 and 3,characterized in that in the diagnosing means, conditions for diagnosingthe abnormality are changeable in accordance with a basis weight and adraw amount of the paper.
 5. The monitoring apparatus according to claim4, characterized by further comprising adjusting means, wherein, whenthe abnormality is diagnosed, the adjusting means adjusts the drawamount in accordance with a result of the diagnosis, thereby preventinga paper tear.
 6. The monitoring apparatus according to claim 1,characterized in that the means for preventing staining of the lightreceiving window of the box is an air curtain flowing across the outersurface of the window.
 7. The monitoring apparatus according to claim 1,characterized in that the means for preventing staining of the lightreceiving window of the box is a coating covering the outer surface ofthe window.